1. Field of the Invention
The present invention relates to novel piperidine derivatives and pharmacologically acceptable salts thereof which have an antihistaminic and antiallergic activity and are useful for the treatment of, for example, bronchial asthma, allergic rhinitis, dermatosis, and urticaria, and to the method for preparation thereof.
The present invention also relates to a pharmaceutical composition comprising the effective amount of the same.
2. Description of the Prior Art
Among the piperidine compounds having a tricyclic ring substituent, for example, dibenzocycloheptene ring or a dibenzoxepine ring, in the 4-position of the piperidine ring, such compound as cyproheptadine (The Merck Index, 11th edition, 2779: 4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-1-methylpiperidine) represented by the following formula: ##STR2## has been developed as an antihistaminic agent and is widely used clinically for the treatment of such ailments as allergic rhinitis and dermatosis.
However, this class of compounds those having a carboxyl or a lower alkoxycarbonyl group in the substituent at the 1-position of the piperidine ring have never been known to date.
A large number of antihistaminic agents have been developed so far and are used for the treatment of, for example, allergic dermatosis or rhinitis. However, adverse reactions of a central inhibitory action caused by the administration of the known antihistaminic agents such as sleepiness or sedation are found to be a great problem with these known agents. In addition, as anticholinergic action which is considered to be one of the possible reasons for hydrodipsia or mydriasis is another undesired adverse reaction of the antihistaminic agents. Various kinds of research have been conducted to solve the above problems, however, presently available antihistaminic agents are insufficient from a clinical point of view.